This invention relates to the field precision optical devices, and more particularly, to mirror panels for retroreflectors, lateral transfer retroreflectors and periscopes.
Retroreflectors are old in the art. A retroreflector receives and reflects an incident light ray so that the incident and reflected light rays travel along parallel paths in opposite directions; i.e., the retroreflector reflects the incident light ray back in the direction from which it came, along a substantially parallel path. A retroreflector normally consists of three optically flat reflecting surfaces formed together in such a way that the each of the three reflecting surfaces are perpendicular to each other. Only in this configuration can the incident and reflected light rays hope to be parallel. Hence, the achievement of reflective parallelism between the incident and reflected light rays depends on both the flatness and the perpendicularity of the three mirror panels.
A lateral transfer retroreflector is similar in construction to a retroreflector, except that one of the mirror panels is offset from the other two, thereby allowing the reflected light ray to not only be reflected back in a parallel orientation to the incident ray, but also at a distance equal to the particular offset distance of the third mirror panel. Such an assembly is described in detail in co-pending U.S. patent application Ser. No. 09/894,207, which is incorporated herein by reference.
Periscopes are also old in the art, and are meant to take an incident light ray and reflect It off of two mirror panels, in a direction substantially parallel to and in the same direction as the Incident ray. So, for example, the most known use for a periscope is in a submarine. Here the person, situated below the surface of the water can nevertheless see above the water surface. This is accomplished because what the person is seeing are hundreds of incident light rays entering the part of the periscope above the water, reflecting off of a mirror panel also above the water, to a mirror panel near the person, below the water (i.e., offset in position from the mirror panel above the water), which is then reflected to the person""s eye. While most common periscope usage does not require exacting parallelism between the incident and reflected rays, there are many uses of periscope that do require such exacting parallelism.
Even retroreflectors, lateral transfer reioreflectors and periscopes made of highly flat mirror panels can lose the parallelism between the incident and reflected light rays, i.e., their accuracy, if they are exposed to physical stresses. Typical examples of the types of stresses that can reduce the accuracy of one of these devices are mass, thermal expansion and contraction of the substrate material from which the assembly of the parts of the device are made, or even deflection of the reflective surfaces during the process of curing the adhesive which typically Joins members of the device to each other; i.e., as the adhesive dries, it shrinks and thereby causes pulling stresses to be exerted upon the various elements of the device. If the accuracies of the device are needed to be extremely high (in the range of 0.0001 degrees of deflection between the incident and reflected rays), then even the smallest of the above stresses causing deflection of the reflective surface of one of the mirror panels will be unacceptable.
As indicated, retroreflectors, lateral transfer retroreflectors and periscopes are old In the art. Examples of prior art retroreflectors and lateral transfer retroreflectors are described in the following patents:
U.S. Pat. No. 3,977,765 to Lipkins, discloses a retroreflector mounted to a support structure through means of applying an adhesive into the joints formed between joined members of the retrorflector and the support structure.
U.S. Pat. No. 4,065,204 also to Lipkins, discloses a lateral transfer retroreflector consisting of a base, a roof reflector having two reflecting plates and a third reflector. The base acts as an extension element for the third reflector in order to provide the offset of the third reflector from the roof reflector to produce the lateral displacement therebetween.
U.S. Pat. No. 5,024,514 to Bleier and Lipkins, discloses a lateral transfer retroreflector having a tubular member, a roof mirror and a mirror panel. Both the roof mirror and mirror panel are attached to the tubular member by use of three co-planar mounting pads.
U.S. Pat. No. 5,301,067 to Bleier and Lipkins, discloses a high accuracy periscope assembly comprised of a hollow tubular member and two mirror panels. The mirror panels are adhered to the tubular member on slanted surfaces of the tubular member along mounting pads.
U.S. Pat. No. 5,361,171 to Bleler, discloses a lateral transfer retroreflector having a fixed-length tubular member, a roof mirror secured within a channel portion extending from an end of the tubular member and a mirror panel attached to the tubular member at the opposite end from the roof mirror and roof mirror panel.
None of the above prior art provides the configuration of the retroreflector and periscope of the present invention, particularly the configuration of the pin mounted mirror panel. It would be desirable to be able to adhere components of precision optical devices together in such a manner as to minimize stresses between the components upon curing, while achieving easy and accurate alignment of the components.
In accordance with the invention, a reflector for a precision optical device is provided. The reflector comprises a reflective surface, a back surface, a thickness between the reflective surface and the back surface defining an edge of the reflector, at least one mounting pad located along at least a portion of the edge of the reflector for adhesion to a portion of the precision optical device, and a mounting pin extending from another portion of the edge of the reflector for adhesion within a hole in the precision optical device.
Accordingly, it is an object of the present invention to provide an improved reflector for a precision optical device.
A further object of the invention is to provide an improved reflector for a precision optical device having a mounting pin instead of a mounting pad.
It is a further object of the invention to provide an improved lateral transfer retroreflector utilizing the improved mounting pin of the Improved reflector.
Yet another object of the invention is to provide an improved periscope assembly utilizing the improved mounting pin of the improved reflector.
Other objects of the invention will in part be obvious and will in part be apparent from the following description.
The invention accordingly comprises assemblies possessing the features, properties and the relation of components which will be exemplified in the products hereinafter described, and the scope of the invention will be indicated in the claims.